Re: [PATCH v2 4/7] ghes_edac: avoid multiple calls to dmi_walk()

Borislav Petkov
2017-08-04T04:05:25Z

On Thu, Aug 03, 2017 at 03:57:50PM -0600, Toshi Kani wrote:
> ghes_edac_register() is called for each GHES platform device
> instantiated per a GHES entry in ACPI HEST table. dmi_walk()
> counts the number of DIMMs on the system, and there is no need
> to call it multiple times.
>
> Change ghes_edac_register() to call dmi_walk() only when
> 'num_dimm' is uninitialized.
>
> Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
> Suggested-by: Borislav Petkov <bp@alien8.de>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
> ---
> drivers/edac/ghes_edac.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/edac/ghes_edac.c b/drivers/edac/ghes_edac.c
> index 4e61a62..2e9ce9c 100644
> --- a/drivers/edac/ghes_edac.c
> +++ b/drivers/edac/ghes_edac.c
> @@ -407,15 +407,18 @@ EXPORT_SYMBOL_GPL(ghes_edac_report_mem_error);
>
> int ghes_edac_register(struct ghes *ghes, struct device *dev)
> {
> - bool fake = false;
> - int rc, num_dimm = 0;
> struct mem_ctl_info *mci;
> struct edac_mc_layer layers[1];
> struct ghes_edac_pvt *pvt;
> struct ghes_edac_dimm_fill dimm_fill;
> + int rc;
> +
> + static int num_dimm;
> + static bool fake;
>
> /* Get the number of DIMMs */
> - dmi_walk(ghes_edac_count_dimms, &num_dimm);
> + if (num_dimm == 0)
> + dmi_walk(ghes_edac_count_dimms, &num_dimm);

So the problem is that ghes_edac_register() gets called multiple times
depending on how many GHES platform devices are on the system. But yet
they all scan *all* DIMMs. So instead you should return if the DIMMs
have been counted already and not register a second time.

Which makes that whole mc counting kinda useless. So you could rip that
out too.

Unless I'm missing something...

--
Regards/Gruss,
Boris.

ECO tip #101: Trim your mails when you reply.
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